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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32697 results found.

  1. GRB 250331D: Fermi GBM observation
  2. GRB 250331C: Swift/UVOT Upper Limits
  3. GRB 250331B: Swift/UVOT Upper Limits
  4. GRB 250328A: AbAO AS-32 Optical Observations
  5. GRB 250219A: NOT candidate host galaxy detection
  6. GRB 250322B: GRBAlpha detection
  7. GRB 250330B: SVOM/GRM observation of a short burst
  8. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  9. Fermi GRB 250331E: Global MASTER-Net observations report
  10. Fermi GRB 250331D: Global MASTER-Net observations report
  11. GRB 250330B: EIRSAT-1 GMOD Detection
  12. GRB 250327A Swift-BAT refined analysis
  13. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  14. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  15. GRB 250331D: Swift ToO observations
  16. Swift GRB 250331C: Global MASTER-Net observations report
  17. Swift GRB 250331B: Global MASTER-Net observations report
  18. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  19. Konus-Wind detection of GRB 250327B
  20. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  21. GRB 250329B: Swift-XRT confirmation of fading
  22. GRB 250330A: VLT/FORS2 Afterglow Detection
  23. GRB20250327B: 45th Parallel Observatory upper limit
  24. GRB 250328A: Swift/UVOT Detection
  25. GRB 250328A: Swift-XRT refined Analysis
  26. Fermi-LAT gamma-ray observations of IceCube-250330A
  27. SVOM/sb25033102 is a false trigger
  28. GRB 250330A: Fermi GBM Observation
  29. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  30. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  31. GRB 250330A: SVOM/VT optical upper limit
  32. GRB 250314A: VLA detection
  33. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  34. Fermi GRB 250330B: Global MASTER-Net observations report
  35. Fermi GRB 250330A: Global MASTER-Net observations report
  36. GRB 250330A: BOOTES-7 early optical upper limit
  37. GRB 250330A: Swift/UVOT Upper Limits
  38. GRB 250328A: 1.6m Mephisto optical observations
  39. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  40. GRB 250330A: Fermi GBM Final Localization
  41. GRB 250330A: VLT/FORS2 Optical Observations
  42. GRB 250330A: Prompt Swift-XRT position
  43. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  44. GRB 250329B: SVOM/C-GFT optical upper limit
  45. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  46. GRB 250327B: ALMA detection
  47. GRB 250327B: VLA detection
  48. GRB 250329B: SVOM/VT optical upper limit
  49. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  50. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  51. GRB250329A: REM optical afterglow detection
  52. GRB 250329B: GWAC-F50A optical upper limit
  53. GRB 250329A: Swift-XRT afterglow detection
  54. GRB 250328A: SVOM/VT optical observation
  55. GRB 250329A: Fading optical counterpart detection by LCO.
  56. GRB 250328A: SVOM/C-GFT optical upper limit
  57. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  58. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  59. GRB 250329A: VLT/X-shooter redshift z = 2.921
  60. GRB 250329A: SVOM/VT optical counterpart confirmation
  61. GRB 250327B: J-band observations with WINTER
  62. GRB 250327B: MASTER detection of OT rebrightening
  63. GRB 250327B: LCO optical counterpart detection
  64. GRB 250328A: GWAC-F50A optical upper limit
  65. FRB 20250316A: FTW optical observations
  66. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  67. GRB 250327B: CrAO and SAO RAS Optical Observations
  68. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  69. GRB 250327B: further optical observations by LCOGT
  70. EP250315a: Pan-STARRS r and i-band imaging and photometry
  71. GRB 250327b: Liverpool Telescope optical observations
  72. GRB 250322A: GRANDMA/TNOT optical upper limits
  73. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  74. GRB 250327A: SVOM/VT upper limits on the XRT position
  75. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  76. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  77. GRB 250327B: Las Cumbres optical counterpart detection
  78. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  79. GRB 250327B: 1.6m Mephisto optical observations
  80. GRB 250327B: NOT spectroscopic redshift z = 3.035
  81. GRB 250327B: GOTO optical counterpart detection
  82. GRB 250327B: SVOM/VT optically bright counterpart
  83. GRB 250327B: SAO RAS optical candidate
  84. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  85. GRB 250327A: J-band observations with WINTER
  86. GRB 250327A: SVOM/VT optical candidate
  87. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  88. GRB 250327A: Fermi GBM observation
  89. Fermi GRB 250327A: Global MASTER-Net observations report
  90. Swift GRB 250327A: Global MASTER-Net observations report
  91. GRB 250327A: DDOTI Optical Observations
  92. GRB 250327A: COLIBRÍ optical upper limit
  93. GRB 250327A: Swift detection of a burst
  94. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  95. Konus-Wind detection of GRB 250322A (short)
  96. IPN triangulation of GRB 250322B
  97. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  98. EP250321a: Mondy AZT-33IK Continued Optical Observations
  99. GRB 250322A: third epoch of NOT optical observations
  100. GRB 250322A: Swift-BAT refined analysis

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